Accurate fuel consumption measurement is very important in improving fuel efficiency in engine powered vehicles. Given the tightening of EPA fuel consumption standards, the need has become crucial for the most accurate fuel consumption measurements in all modes of operation including at idle.
The use of Coriolis mass flow rate meters has become fairly popular in measuring fuel flow rates in single engine or multi-engine fuel measurement systems. They have been used in natural gas systems, diesel systems and many other applications, and are considered very effective in measuring fuel flow rate in these different applications. These meters operate on the principle of flowing a fluid through an oscillating conduit, thereby producing forces perpendicular to both the velocity of the mass moving through the conduit and the angular velocity vector of the oscillation of the conduit. The magnitude of such forces is related to the mass flow rate as a function of the angular velocity of the conduit in that the meter has a vibrating U-shaped tube which twists under these forces an amount proportional to the mass flow rate of the fluid therethrough. However, the accuracy of these meters is drastically compromised at very low flow rates, such as at engine idle and near idle engine speeds, thereby precluding their use at this particular range of engine operation.
Therefore, it is desirable to develop a method of using Coriolis mass flow rate meters in a manner which would increase the measurement accuracy of the meter and allow its use at even the lowest fuel flow rates.